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commit 40f567bbb3b0639d2ec7d1c6ad4b1b018f80cf19 upstream.
The function kzalloc() in detached_dev_do_request() can fail, so its
return value should be checked.
Fixes: bc082a55d25c ("bcache: fix inaccurate io state for detached bcache devices")
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Link: https://lore.kernel.org/r/20220527152818.27545-4-colyli@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 224b0683228c5f332f9cee615d85e75e9a347170 ]
Except for the IDA none of the allocations in bcache_device_init is
unwound on error, fix that.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Coly Li <colyli@suse.de>
Link: https://lore.kernel.org/r/20210809064028.1198327-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 34cf78bf34d48dddddfeeadb44f9841d7864997a ]
This patch fix a lost wake-up problem caused by the race between
mca_cannibalize_lock and bch_cannibalize_unlock.
Consider two processes, A and B. Process A is executing
mca_cannibalize_lock, while process B takes c->btree_cache_alloc_lock
and is executing bch_cannibalize_unlock. The problem happens that after
process A executes cmpxchg and will execute prepare_to_wait. In this
timeslice process B executes wake_up, but after that process A executes
prepare_to_wait and set the state to TASK_INTERRUPTIBLE. Then process A
goes to sleep but no one will wake up it. This problem may cause bcache
device to dead.
Signed-off-by: Guoju Fang <fangguoju@gmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 7a1481267999c02abf4a624515c1b5c7c1fccbd6 upstream.
offset_to_stripe() returns the stripe number (in type unsigned int) from
an offset (in type uint64_t) by the following calculation,
do_div(offset, d->stripe_size);
For large capacity backing device (e.g. 18TB) with small stripe size
(e.g. 4KB), the result is 4831838208 and exceeds UINT_MAX. The actual
returned value which caller receives is 536870912, due to the overflow.
Indeed in bcache_device_init(), bcache_device->nr_stripes is limited in
range [1, INT_MAX]. Therefore all valid stripe numbers in bcache are
in range [0, bcache_dev->nr_stripes - 1].
This patch adds a upper limition check in offset_to_stripe(): the max
valid stripe number should be less than bcache_device->nr_stripes. If
the calculated stripe number from do_div() is equal to or larger than
bcache_device->nr_stripe, -EINVAL will be returned. (Normally nr_stripes
is less than INT_MAX, exceeding upper limitation doesn't mean overflow,
therefore -EOVERFLOW is not used as error code.)
This patch also changes nr_stripes' type of struct bcache_device from
'unsigned int' to 'int', and return value type of offset_to_stripe()
from 'unsigned int' to 'int', to match their exact data ranges.
All locations where bcache_device->nr_stripes and offset_to_stripe() are
referenced also get updated for the above type change.
Reported-and-tested-by: Ken Raeburn <raeburn@redhat.com>
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1783075
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5fe48867856367142d91a82f2cbf7a57a24cbb70 upstream.
There are some meta data of bcache are allocated by multiple pages,
and they are used as bio bv_page for I/Os to the cache device. for
example cache_set->uuids, cache->disk_buckets, journal_write->data,
bset_tree->data.
For such meta data memory, all the allocated pages should be treated
as a single memory block. Then the memory management and underlying I/O
code can treat them more clearly.
This patch adds __GFP_COMP flag to all the location allocating >0 order
pages for the above mentioned meta data. Then their pages are treated
as compound pages now.
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 117f636ea695270fe492d0c0c9dfadc7a662af47 ]
In register_cache_set(), c is pointer to struct cache_set, and ca is
pointer to struct cache, if ca->sb.seq > c->sb.seq, it means this
registering cache has up to date version and other members, the in-
memory version and other members should be updated to the newer value.
But current implementation makes a cache set only has a single cache
device, so the above assumption works well except for a special case.
The execption is when a cache device new created and both ca->sb.seq and
c->sb.seq are 0, because the super block is never flushed out yet. In
the location for the following if() check,
2156 if (ca->sb.seq > c->sb.seq) {
2157 c->sb.version = ca->sb.version;
2158 memcpy(c->sb.set_uuid, ca->sb.set_uuid, 16);
2159 c->sb.flags = ca->sb.flags;
2160 c->sb.seq = ca->sb.seq;
2161 pr_debug("set version = %llu\n", c->sb.version);
2162 }
c->sb.version is not initialized yet and valued 0. When ca->sb.seq is 0,
the if() check will fail (because both values are 0), and the cache set
version, set_uuid, flags and seq won't be updated.
The above problem is hiden for current code, because the bucket size is
compatible among different super block version. And the next time when
running cache set again, ca->sb.seq will be larger than 0 and cache set
super block version will be updated properly.
But if the large bucket feature is enabled, sb->bucket_size is the low
16bits of the bucket size. For a power of 2 value, when the actual
bucket size exceeds 16bit width, sb->bucket_size will always be 0. Then
read_super_common() will fail because the if() check to
is_power_of_2(sb->bucket_size) is false. This is how the long time
hidden bug is triggered.
This patch modifies the if() check to the following way,
2156 if (ca->sb.seq > c->sb.seq || c->sb.seq == 0) {
Then cache set's version, set_uuid, flags and seq will always be updated
corectly including for a new created cache device.
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit be23e837333a914df3f24bf0b32e87b0331ab8d1 ]
coccicheck reports:
drivers/md//bcache/btree.c:1538:1-7: preceding lock on line 1417
In btree_gc_coalesce func, if the coalescing process fails, we will goto
to out_nocoalesce tag directly without releasing new_nodes[i]->write_lock.
Then, it will cause a deadlock when trying to acquire new_nodes[i]->
write_lock for freeing new_nodes[i] before return.
btree_gc_coalesce func details as follows:
if alloc new_nodes[i] fails:
goto out_nocoalesce;
// obtain new_nodes[i]->write_lock
mutex_lock(&new_nodes[i]->write_lock)
// main coalescing process
for (i = nodes - 1; i > 0; --i)
[snipped]
if coalescing process fails:
// Here, directly goto out_nocoalesce
// tag will cause a deadlock
goto out_nocoalesce;
[snipped]
// release new_nodes[i]->write_lock
mutex_unlock(&new_nodes[i]->write_lock)
// coalesing succ, return
return;
out_nocoalesce:
btree_node_free(new_nodes[i]) // free new_nodes[i]
// obtain new_nodes[i]->write_lock
mutex_lock(&new_nodes[i]->write_lock);
// set flag for reuse
clear_bit(BTREE_NODE_dirty, &ew_nodes[i]->flags);
// release new_nodes[i]->write_lock
mutex_unlock(&new_nodes[i]->write_lock);
To fix the problem, we add a new tag 'out_unlock_nocoalesce' for
releasing new_nodes[i]->write_lock before out_nocoalesce tag. If
coalescing process fails, we will go to out_unlock_nocoalesce tag
for releasing new_nodes[i]->write_lock before free new_nodes[i] in
out_nocoalesce tag.
(Coly Li helps to clean up commit log format.)
Fixes: 2a285686c109816 ("bcache: btree locking rework")
Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 86da9f736740eba602389908574dfbb0f517baa5 ]
The problematic code piece in bcache_device_free() is,
785 static void bcache_device_free(struct bcache_device *d)
786 {
787 struct gendisk *disk = d->disk;
[snipped]
799 if (disk) {
800 if (disk->flags & GENHD_FL_UP)
801 del_gendisk(disk);
802
803 if (disk->queue)
804 blk_cleanup_queue(disk->queue);
805
806 ida_simple_remove(&bcache_device_idx,
807 first_minor_to_idx(disk->first_minor));
808 put_disk(disk);
809 }
[snipped]
816 }
At line 808, put_disk(disk) may encounter kobject refcount of 'disk'
being underflow.
Here is how to reproduce the issue,
- Attche the backing device to a cache device and do random write to
make the cache being dirty.
- Stop the bcache device while the cache device has dirty data of the
backing device.
- Only register the backing device back, NOT register cache device.
- The bcache device node /dev/bcache0 won't show up, because backing
device waits for the cache device shows up for the missing dirty
data.
- Now echo 1 into /sys/fs/bcache/pendings_cleanup, to stop the pending
backing device.
- After the pending backing device stopped, use 'dmesg' to check kernel
message, a use-after-free warning from KASA reported the refcount of
kobject linked to the 'disk' is underflow.
The dropping refcount at line 808 in the above code piece is added by
add_disk(d->disk) in bch_cached_dev_run(). But in the above condition
the cache device is not registered, bch_cached_dev_run() has no chance
to be called and the refcount is not added. The put_disk() for a non-
added refcount of gendisk kobject triggers a underflow warning.
This patch checks whether GENHD_FL_UP is set in disk->flags, if it is
not set then the bcache device was not added, don't call put_disk()
and the the underflow issue can be avoided.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 7c02b0055f774ed9afb6e1c7724f33bf148ffdc0 ]
In bset.h, macro bset_bkey_last() is defined as,
bkey_idx((struct bkey *) (i)->d, (i)->keys)
Parameter i can be variable type of data structure, the macro always
works once the type of struct i has member 'd' and 'keys'.
bset_bkey_last() is also used in macro csum_set() to calculate the
checksum of a on-disk data structure. When csum_set() is used to
calculate checksum of on-disk bcache super block, the parameter 'i'
data type is struct cache_sb_disk. Inside struct cache_sb_disk (also in
struct cache_sb) the member keys is __u16 type. But bkey_idx() expects
unsigned int (a 32bit width), so there is problem when sending
parameters via stack to call bkey_idx().
Sparse tool from Intel 0day kbuild system reports this incompatible
problem. bkey_idx() is part of user space API, so the simplest fix is
to cast the (i)->keys to unsigned int type in macro bset_bkey_last().
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e8547d42095e58bee658f00fef8e33d2a185c927 ]
Same as cache device, the buffer page needs to be put while
freeing cached_dev. Otherwise a page would be leaked every
time a cached_dev is stopped.
Signed-off-by: Liang Chen <liangchen.linux@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 038ba8cc1bffc51250add4a9b9249d4331576d8f upstream.
In year 2007 high performance SSD was still expensive, in order to
save more space for real workload or meta data, the readahead I/Os
for non-meta data was bypassed and not cached on SSD.
In now days, SSD price drops a lot and people can find larger size
SSD with more comfortable price. It is unncessary to alway bypass
normal readahead I/Os to save SSD space for now.
This patch adds options for readahead data cache policies via sysfs
file /sys/block/bcache<N>/readahead_cache_policy, the options are,
- "all": cache all readahead data I/Os.
- "meta-only": only cache meta data, and bypass other regular I/Os.
If users want to make bcache continue to only cache readahead request
for metadata and bypass regular data readahead, please set "meta-only"
to this sysfs file. By default, bcache will back to cache all read-
ahead requests now.
Cc: stable@vger.kernel.org
Signed-off-by: Coly Li <colyli@suse.de>
Acked-by: Eric Wheeler <bcache@linux.ewheeler.net>
Cc: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit d66c9920c0cf984cf99cab5036fd5f3a1b7fba46 ]
The copy_to_user() function returns the number of bytes remaining to be
copied, but the intention here was to return -EFAULT if the copy fails.
Fixes: cafe56359144 ("bcache: A block layer cache")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 9fcc34b1a6dd4b8e5337e2b6ef45e428897eca6b ]
In bch_mca_scan(), the number of shrinking btree node is calculated
by code like this,
unsigned long nr = sc->nr_to_scan;
nr /= c->btree_pages;
nr = min_t(unsigned long, nr, mca_can_free(c));
variable sc->nr_to_scan is number of objects (here is bcache B+tree
nodes' number) to shrink, and pointer variable sc is sent from memory
management code as parametr of a callback.
If sc->nr_to_scan is smaller than c->btree_pages, after the above
calculation, variable 'nr' will be 0 and nothing will be shrunk. It is
frequeently observed that only 1 or 2 is set to sc->nr_to_scan and make
nr to be zero. Then bch_mca_scan() will do nothing more then acquiring
and releasing mutex c->bucket_lock.
This patch checkes whether nr is 0 after the above calculation, if 0
is the result then set 1 to variable 'n'. Then at least bch_mca_scan()
will try to shrink a single B+tree node.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 84c529aea182939e68f618ed9813740c9165c7eb ]
bcache_allocator can call the following:
bch_allocator_thread()
-> bch_prio_write()
-> bch_bucket_alloc()
-> wait on &ca->set->bucket_wait
But the wake up event on bucket_wait is supposed to come from
bch_allocator_thread() itself => deadlock:
[ 1158.490744] INFO: task bcache_allocato:15861 blocked for more than 10 seconds.
[ 1158.495929] Not tainted 5.3.0-050300rc3-generic #201908042232
[ 1158.500653] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1158.504413] bcache_allocato D 0 15861 2 0x80004000
[ 1158.504419] Call Trace:
[ 1158.504429] __schedule+0x2a8/0x670
[ 1158.504432] schedule+0x2d/0x90
[ 1158.504448] bch_bucket_alloc+0xe5/0x370 [bcache]
[ 1158.504453] ? wait_woken+0x80/0x80
[ 1158.504466] bch_prio_write+0x1dc/0x390 [bcache]
[ 1158.504476] bch_allocator_thread+0x233/0x490 [bcache]
[ 1158.504491] kthread+0x121/0x140
[ 1158.504503] ? invalidate_buckets+0x890/0x890 [bcache]
[ 1158.504506] ? kthread_park+0xb0/0xb0
[ 1158.504510] ret_from_fork+0x35/0x40
Fix by making the call to bch_prio_write() non-blocking, so that
bch_allocator_thread() never waits on itself.
Moreover, make sure to wake up the garbage collector thread when
bch_prio_write() is failing to allocate buckets.
BugLink: https://bugs.launchpad.net/bugs/1784665
BugLink: https://bugs.launchpad.net/bugs/1796292
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 2d8869518a525c9bce5f5268419df9dfbe3dfdeb ]
Commit cafe56359144 ("bcache: A block layer cache") leads to the
following static checker warning:
./drivers/md/bcache/super.c:770 bcache_device_free()
warn: variable dereferenced before check 'd->disk' (see line 766)
drivers/md/bcache/super.c
762 static void bcache_device_free(struct bcache_device *d)
763 {
764 lockdep_assert_held(&bch_register_lock);
765
766 pr_info("%s stopped", d->disk->disk_name);
^^^^^^^^^
Unchecked dereference.
767
768 if (d->c)
769 bcache_device_detach(d);
770 if (d->disk && d->disk->flags & GENHD_FL_UP)
^^^^^^^
Check too late.
771 del_gendisk(d->disk);
772 if (d->disk && d->disk->queue)
773 blk_cleanup_queue(d->disk->queue);
774 if (d->disk) {
775 ida_simple_remove(&bcache_device_idx,
776 first_minor_to_idx(d->disk->first_minor));
777 put_disk(d->disk);
778 }
779
It is not 100% sure that the gendisk struct of bcache device will always
be there, the warning makes sense when there is problem in block core.
This patch tries to remove the static checking warning by checking
d->disk to avoid NULL pointer deferences.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 79b791466e525c98f6aeee9acf5726e7b27f4231 ]
A fresh backing device is not attached to any cache_set, and
has no writeback kthread created until first attached to some
cache_set.
But bch_cached_dev_writeback_init run
"
dc->writeback_running = true;
WARN_ON(test_and_clear_bit(BCACHE_DEV_WB_RUNNING,
&dc->disk.flags));
"
for any newly formatted backing devices.
For a fresh standalone backing device, we can get something like
following even if no writeback kthread created:
------------------------
/sys/block/bcache0/bcache# cat writeback_running
1
/sys/block/bcache0/bcache# cat writeback_rate_debug
rate: 512.0k/sec
dirty: 0.0k
target: 0.0k
proportional: 0.0k
integral: 0.0k
change: 0.0k/sec
next io: -15427384ms
The none ZERO fields are misleading as no alive writeback kthread yet.
Set dc->writeback_running false as no writeback thread created in
bch_cached_dev_writeback_init().
We have writeback thread created and woken up in bch_cached_dev_writeback
_start(). Set dc->writeback_running true before bch_writeback_queue()
called, as a writeback thread will check if dc->writeback_running is true
before writing back dirty data, and hung if false detected.
After the change, we can get the following output for a fresh standalone
backing device:
-----------------------
/sys/block/bcache0/bcache$ cat writeback_running
0
/sys/block/bcache0/bcache# cat writeback_rate_debug
rate: 0.0k/sec
dirty: 0.0k
target: 0.0k
proportional: 0.0k
integral: 0.0k
change: 0.0k/sec
next io: 0ms
v1 -> v2:
Set dc->writeback_running before bch_writeback_queue() called,
Signed-off-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit ae17102316550b4b230a283febe31b2a9ff30084 ]
debugfs_remove and debugfs_remove_recursive will check if the dentry
pointer is NULL or ERR, and will do nothing in that case.
Remove the check in cache_set_free and bch_debug_init.
Signed-off-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 46010141da6677b81cc77f9b47f8ac62bd1cbfd3 ]
Recal cached_dev_sectors on cached_dev detached, as recal done on
cached_dev attached.
Update the cached_dev_sectors before bcache_device_detach called
as bcache_device_detach will set bcache_device->c to NULL.
Signed-off-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 7a55948d38eb9b274cbbdd56dc1dd4b96ebfbe04 ]
UUIDs are considered as metadata. __uuid_write should add the number
of buckets (in sectors) written to disk to ca->meta_sectors_written.
Currently only 1 bucket is used in uuid write.
Steps to test:
1) create a fresh backing device and a fresh cache device separately.
The backing device didn't attach to any cache set.
2) cd /sys/block/<cache device>/bcache
cat metadata_written // record the output value
cat bucket_size
3) attach the backing device to cache set
4) cat metadata_written
The output value is almost the same as the value in step 2
before the change.
After the change, the value is bigger about 1 bucket size.
Signed-off-by: Shenghui Wang <shhuiw@foxmail.com>
Reviewed-by: Tang Junhui <tang.junhui.linux@gmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit dab71b2db98dcdd4657d151b01a7be88ce10f9d1 ]
dc->writeback_rate_minimum is type unsigned integer variable, it is set
via sysfs interface, and converte from input string to unsigned integer
by d_strtoul_nonzero(). When the converted input value is larger than
UINT_MAX, overflow to unsigned integer happens.
This patch fixes the overflow by using sysfs_strotoul_clamp() to
convert input string and limit the value in range [1, UINT_MAX], then
the overflow can be avoided.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit a22a9602b88fabf10847f238ff81fde5f906fef7 ]
The race was when a thread using closure_sync() notices cl->s->done == 1
before the thread calling closure_put() calls wake_up_process(). Then,
it's possible for that thread to return and exit just before
wake_up_process() is called - so we're trying to wake up a process that
no longer exists.
rcu_read_lock() is sufficient to protect against this, as there's an rcu
barrier somewhere in the process teardown path.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Acked-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit cdca22bcbc64fc83dadb8d927df400a8d86ddabb ]
Commit 95f18c9d1310 ("bcache: avoid potential memleak of list of
journal_replay(s) in the CACHE_SYNC branch of run_cache_set") forgets
to remove the original define of LIST_HEAD(journal), which makes
the change no take effect. This patch removes redundant variable
LIST_HEAD(journal) from run_cache_set(), to make Shenghui's fix
working.
Fixes: 95f18c9d1310 ("bcache: avoid potential memleak of list of journal_replay(s) in the CACHE_SYNC branch of run_cache_set")
Reported-by: Juha Aatrokoski <juha.aatrokoski@aalto.fi>
Cc: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 50a260e859964002dab162513a10f91ae9d3bcd3 ]
There is a race between mca_reap(), btree_node_free() and journal code
btree_flush_write(), which results very rare and strange deadlock or
panic and are very hard to reproduce.
Let me explain how the race happens. In btree_flush_write() one btree
node with oldest journal pin is selected, then it is flushed to cache
device, the select-and-flush is a two steps operation. Between these two
steps, there are something may happen inside the race window,
- The selected btree node was reaped by mca_reap() and allocated to
other requesters for other btree node.
- The slected btree node was selected, flushed and released by mca
shrink callback bch_mca_scan().
When btree_flush_write() tries to flush the selected btree node, firstly
b->write_lock is held by mutex_lock(). If the race happens and the
memory of selected btree node is allocated to other btree node, if that
btree node's write_lock is held already, a deadlock very probably
happens here. A worse case is the memory of the selected btree node is
released, then all references to this btree node (e.g. b->write_lock)
will trigger NULL pointer deference panic.
This race was introduced in commit cafe56359144 ("bcache: A block layer
cache"), and enlarged by commit c4dc2497d50d ("bcache: fix high CPU
occupancy during journal"), which selected 128 btree nodes and flushed
them one-by-one in a quite long time period.
Such race is not easy to reproduce before. On a Lenovo SR650 server with
48 Xeon cores, and configure 1 NVMe SSD as cache device, a MD raid0
device assembled by 3 NVMe SSDs as backing device, this race can be
observed around every 10,000 times btree_flush_write() gets called. Both
deadlock and kernel panic all happened as aftermath of the race.
The idea of the fix is to add a btree flag BTREE_NODE_journal_flush. It
is set when selecting btree nodes, and cleared after btree nodes
flushed. Then when mca_reap() selects a btree node with this bit set,
this btree node will be skipped. Since mca_reap() only reaps btree node
without BTREE_NODE_journal_flush flag, such race is avoided.
Once corner case should be noticed, that is btree_node_free(). It might
be called in some error handling code path. For example the following
code piece from btree_split(),
2149 err_free2:
2150 bkey_put(b->c, &n2->key);
2151 btree_node_free(n2);
2152 rw_unlock(true, n2);
2153 err_free1:
2154 bkey_put(b->c, &n1->key);
2155 btree_node_free(n1);
2156 rw_unlock(true, n1);
At line 2151 and 2155, the btree node n2 and n1 are released without
mac_reap(), so BTREE_NODE_journal_flush also needs to be checked here.
If btree_node_free() is called directly in such error handling path,
and the selected btree node has BTREE_NODE_journal_flush bit set, just
delay for 1 us and retry again. In this case this btree node won't
be skipped, just retry until the BTREE_NODE_journal_flush bit cleared,
and free the btree node memory.
Fixes: cafe56359144 ("bcache: A block layer cache")
Signed-off-by: Coly Li <colyli@suse.de>
Reported-and-tested-by: kbuild test robot <lkp@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 41508bb7d46b74dba631017e5a702a86caf1db8c ]
When accessing or modifying BTREE_NODE_dirty bit, it is not always
necessary to acquire b->write_lock. In bch_btree_cache_free() and
mca_reap() acquiring b->write_lock is necessary, and this patch adds
comments to explain why mutex_lock(&b->write_lock) is necessary for
checking or clearing BTREE_NODE_dirty bit there.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e5ec5f4765ada9c75fb3eee93a6e72f0e50599d5 ]
In bch_btree_cache_free() and btree_node_free(), BTREE_NODE_dirty is
always set no matter btree node is dirty or not. The code looks like
this,
if (btree_node_dirty(b))
btree_complete_write(b, btree_current_write(b));
clear_bit(BTREE_NODE_dirty, &b->flags);
Indeed if btree_node_dirty(b) returns false, it means BTREE_NODE_dirty
bit is cleared, then it is unnecessary to clear the bit again.
This patch only clears BTREE_NODE_dirty when btree_node_dirty(b) is
true (the bit is set), to save a few CPU cycles.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 58ac323084ebf44f8470eeb8b82660f9d0ee3689 ]
Stale && dirty keys can be produced in the follow way:
After writeback in write_dirty_finish(), dirty keys k1 will
replace by clean keys k2
==>ret = bch_btree_insert(dc->disk.c, &keys, NULL, &w->key);
==>btree_insert_fn(struct btree_op *b_op, struct btree *b)
==>static int bch_btree_insert_node(struct btree *b,
struct btree_op *op,
struct keylist *insert_keys,
atomic_t *journal_ref,
Then two steps:
A) update k1 to k2 in btree node memory;
bch_btree_insert_keys(b, op, insert_keys, replace_key)
B) Write the bset(contains k2) to cache disk by a 30s delay work
bch_btree_leaf_dirty(b, journal_ref).
But before the 30s delay work write the bset to cache device,
these things happened:
A) GC works, and reclaim the bucket k2 point to;
B) Allocator works, and invalidate the bucket k2 point to,
and increase the gen of the bucket, and place it into free_inc
fifo;
C) Until now, the 30s delay work still does not finish work,
so in the disk, the key still is k1, it is dirty and stale
(its gen is smaller than the gen of the bucket). and then the
machine power off suddenly happens;
D) When the machine power on again, after the btree reconstruction,
the stale dirty key appear.
In bch_extent_bad(), when expensive_debug_checks is off, it would
treat the dirty key as good even it is stale keys, and it would
cause bellow probelms:
A) In read_dirty() it would cause machine crash:
BUG_ON(ptr_stale(dc->disk.c, &w->key, 0));
B) It could be worse when reads hits stale dirty keys, it would
read old incorrect data.
This patch tolerate the existence of these stale && dirty keys,
and treat them as bad key in bch_extent_bad().
(Coly Li: fix indent which was modified by sender's email client)
Signed-off-by: Tang Junhui <tang.junhui.linux@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 149d0efada7777ad5a5242b095692af142f533d8 ]
In extents.c:bch_extent_bad(), number 96 is used as parameter to call
btree_bug_on(). The purpose is to check whether stale gen value exceeds
BUCKET_GC_GEN_MAX, so it is better to use macro BUCKET_GC_GEN_MAX to
make the code more understandable.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit f54d801dda14942dbefa00541d10603015b7859c upstream.
Commit 9baf30972b55 ("bcache: fix for gc and write-back race") added a
new work queue dc->writeback_write_wq, but forgot to destroy it in the
error condition when creating dc->writeback_thread failed.
This patch destroys dc->writeback_write_wq if kthread_create() returns
error pointer to dc->writeback_thread, then a memory leak is avoided.
Fixes: 9baf30972b55 ("bcache: fix for gc and write-back race")
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5461999848e0462c14f306a62923d22de820a59c upstream.
In bch_cached_dev_files[] from driver/md/bcache/sysfs.c, sysfs_errors is
incorrectly inserted in. The correct entry should be sysfs_io_errors.
This patch fixes the problem and now I/O errors of cached device can be
read from /sys/block/bcache<N>/bcache/io_errors.
Fixes: c7b7bd07404c5 ("bcache: add io_disable to struct cached_dev")
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 578df99b1b0531d19af956530fe4da63d01a1604 upstream.
When md raid device (e.g. raid456) is used as backing device, read-ahead
requests on a degrading and recovering md raid device might be failured
immediately by md raid code, but indeed this md raid array can still be
read or write for normal I/O requests. Therefore such failed read-ahead
request are not real hardware failure. Further more, after degrading and
recovering accomplished, read-ahead requests will be handled by md raid
array again.
For such condition, I/O failures of read-ahead requests don't indicate
real health status (because normal I/O still be served), they should not
be counted into I/O error counter dc->io_errors.
Since there is no simple way to detect whether the backing divice is a
md raid device, this patch simply ignores I/O failures for read-ahead
bios on backing device, to avoid bogus backing device failure on a
degrading md raid array.
Suggested-and-tested-by: Thorsten Knabe <linux@thorsten-knabe.de>
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ba82c1ac1667d6efb91a268edb13fc9cdaecec9b upstream.
This reverts commit 6268dc2c4703aabfb0b35681be709acf4c2826c6.
This patch depends on commit c4dc2497d50d ("bcache: fix high CPU
occupancy during journal") which is reverted in previous patch. So
revert this one too.
Fixes: 6268dc2c4703 ("bcache: free heap cache_set->flush_btree in bch_journal_free")
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Cc: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 249a5f6da57c28a903c75d81505d58ec8c10030d upstream.
This reverts commit c4dc2497d50d9c6fb16aa0d07b6a14f3b2adb1e0.
This patch enlarges a race between normal btree flush code path and
flush_btree_write(), which causes deadlock when journal space is
exhausted. Reverts this patch makes the race window from 128 btree
nodes to only 1 btree nodes.
Fixes: c4dc2497d50d ("bcache: fix high CPU occupancy during journal")
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Cc: Tang Junhui <tang.junhui.linux@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 695277f16b3a102fcc22c97fdf2de77c7b19f0b3 upstream.
This reverts commit 6147305c73e4511ca1a975b766b97a779d442567.
Although this patch helps the failed bcache device to stop faster when
too many I/O errors detected on corresponding cached device, setting
CACHE_SET_IO_DISABLE bit to cache set c->flags was not a good idea. This
operation will disable all I/Os on cache set, which means other attached
bcache devices won't work neither.
Without this patch, the failed bcache device can also be stopped
eventually if internal I/O accomplished (e.g. writeback). Therefore here
I revert it.
Fixes: 6147305c73e4 ("bcache: set CACHE_SET_IO_DISABLE in bch_cached_dev_error()")
Reported-by: Yong Li <mr.liyong@qq.com>
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 7e865eba00a3df2dc8c4746173a8ca1c1c7f042e ]
When enable lockdep and reboot system with a writeback mode bcache
device, the following potential deadlock warning is reported by lockdep
engine.
[ 101.536569][ T401] kworker/2:2/401 is trying to acquire lock:
[ 101.538575][ T401] 00000000bbf6e6c7 ((wq_completion)bcache_writeback_wq){+.+.}, at: flush_workqueue+0x87/0x4c0
[ 101.542054][ T401]
[ 101.542054][ T401] but task is already holding lock:
[ 101.544587][ T401] 00000000f5f305b3 ((work_completion)(&cl->work)#2){+.+.}, at: process_one_work+0x21e/0x640
[ 101.548386][ T401]
[ 101.548386][ T401] which lock already depends on the new lock.
[ 101.548386][ T401]
[ 101.551874][ T401]
[ 101.551874][ T401] the existing dependency chain (in reverse order) is:
[ 101.555000][ T401]
[ 101.555000][ T401] -> #1 ((work_completion)(&cl->work)#2){+.+.}:
[ 101.557860][ T401] process_one_work+0x277/0x640
[ 101.559661][ T401] worker_thread+0x39/0x3f0
[ 101.561340][ T401] kthread+0x125/0x140
[ 101.562963][ T401] ret_from_fork+0x3a/0x50
[ 101.564718][ T401]
[ 101.564718][ T401] -> #0 ((wq_completion)bcache_writeback_wq){+.+.}:
[ 101.567701][ T401] lock_acquire+0xb4/0x1c0
[ 101.569651][ T401] flush_workqueue+0xae/0x4c0
[ 101.571494][ T401] drain_workqueue+0xa9/0x180
[ 101.573234][ T401] destroy_workqueue+0x17/0x250
[ 101.575109][ T401] cached_dev_free+0x44/0x120 [bcache]
[ 101.577304][ T401] process_one_work+0x2a4/0x640
[ 101.579357][ T401] worker_thread+0x39/0x3f0
[ 101.581055][ T401] kthread+0x125/0x140
[ 101.582709][ T401] ret_from_fork+0x3a/0x50
[ 101.584592][ T401]
[ 101.584592][ T401] other info that might help us debug this:
[ 101.584592][ T401]
[ 101.588355][ T401] Possible unsafe locking scenario:
[ 101.588355][ T401]
[ 101.590974][ T401] CPU0 CPU1
[ 101.592889][ T401] ---- ----
[ 101.594743][ T401] lock((work_completion)(&cl->work)#2);
[ 101.596785][ T401] lock((wq_completion)bcache_writeback_wq);
[ 101.600072][ T401] lock((work_completion)(&cl->work)#2);
[ 101.602971][ T401] lock((wq_completion)bcache_writeback_wq);
[ 101.605255][ T401]
[ 101.605255][ T401] *** DEADLOCK ***
[ 101.605255][ T401]
[ 101.608310][ T401] 2 locks held by kworker/2:2/401:
[ 101.610208][ T401] #0: 00000000cf2c7d17 ((wq_completion)events){+.+.}, at: process_one_work+0x21e/0x640
[ 101.613709][ T401] #1: 00000000f5f305b3 ((work_completion)(&cl->work)#2){+.+.}, at: process_one_work+0x21e/0x640
[ 101.617480][ T401]
[ 101.617480][ T401] stack backtrace:
[ 101.619539][ T401] CPU: 2 PID: 401 Comm: kworker/2:2 Tainted: G W 5.2.0-rc4-lp151.20-default+ #1
[ 101.623225][ T401] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/13/2018
[ 101.627210][ T401] Workqueue: events cached_dev_free [bcache]
[ 101.629239][ T401] Call Trace:
[ 101.630360][ T401] dump_stack+0x85/0xcb
[ 101.631777][ T401] print_circular_bug+0x19a/0x1f0
[ 101.633485][ T401] __lock_acquire+0x16cd/0x1850
[ 101.635184][ T401] ? __lock_acquire+0x6a8/0x1850
[ 101.636863][ T401] ? lock_acquire+0xb4/0x1c0
[ 101.638421][ T401] ? find_held_lock+0x34/0xa0
[ 101.640015][ T401] lock_acquire+0xb4/0x1c0
[ 101.641513][ T401] ? flush_workqueue+0x87/0x4c0
[ 101.643248][ T401] flush_workqueue+0xae/0x4c0
[ 101.644832][ T401] ? flush_workqueue+0x87/0x4c0
[ 101.646476][ T401] ? drain_workqueue+0xa9/0x180
[ 101.648303][ T401] drain_workqueue+0xa9/0x180
[ 101.649867][ T401] destroy_workqueue+0x17/0x250
[ 101.651503][ T401] cached_dev_free+0x44/0x120 [bcache]
[ 101.653328][ T401] process_one_work+0x2a4/0x640
[ 101.655029][ T401] worker_thread+0x39/0x3f0
[ 101.656693][ T401] ? process_one_work+0x640/0x640
[ 101.658501][ T401] kthread+0x125/0x140
[ 101.660012][ T401] ? kthread_create_worker_on_cpu+0x70/0x70
[ 101.661985][ T401] ret_from_fork+0x3a/0x50
[ 101.691318][ T401] bcache: bcache_device_free() bcache0 stopped
Here is how the above potential deadlock may happen in reboot/shutdown
code path,
1) bcache_reboot() is called firstly in the reboot/shutdown code path,
then in bcache_reboot(), bcache_device_stop() is called.
2) bcache_device_stop() sets BCACHE_DEV_CLOSING on d->falgs, then call
closure_queue(&d->cl) to invoke cached_dev_flush(). And in turn
cached_dev_flush() calls cached_dev_free() via closure_at()
3) In cached_dev_free(), after stopped writebach kthread
dc->writeback_thread, the kwork dc->writeback_write_wq is stopping by
destroy_workqueue().
4) Inside destroy_workqueue(), drain_workqueue() is called. Inside
drain_workqueue(), flush_workqueue() is called. Then wq->lockdep_map
is acquired by lock_map_acquire() in flush_workqueue(). After the
lock acquired the rest part of flush_workqueue() just wait for the
workqueue to complete.
5) Now we look back at writeback thread routine bch_writeback_thread(),
in the main while-loop, write_dirty() is called via continue_at() in
read_dirty_submit(), which is called via continue_at() in while-loop
level called function read_dirty(). Inside write_dirty() it may be
re-called on workqueeu dc->writeback_write_wq via continue_at().
It means when the writeback kthread is stopped in cached_dev_free()
there might be still one kworker queued on dc->writeback_write_wq
to execute write_dirty() again.
6) Now this kworker is scheduled on dc->writeback_write_wq to run by
process_one_work() (which is called by worker_thread()). Before
calling the kwork routine, wq->lockdep_map is acquired.
7) But wq->lockdep_map is acquired already in step 4), so a A-A lock
(lockdep terminology) scenario happens.
Indeed on multiple cores syatem, the above deadlock is very rare to
happen, just as the code comments in process_one_work() says,
2263 * AFAICT there is no possible deadlock scenario between the
2264 * flush_work() and complete() primitives (except for
single-threaded
2265 * workqueues), so hiding them isn't a problem.
But it is still good to fix such lockdep warning, even no one running
bcache on single core system.
The fix is simple. This patch solves the above potential deadlock by,
- Do not destroy workqueue dc->writeback_write_wq in cached_dev_free().
- Flush and destroy dc->writeback_write_wq in writebach kthread routine
bch_writeback_thread(), where after quit the thread main while-loop
and before cached_dev_put() is called.
By this fix, dc->writeback_write_wq will be stopped and destroy before
the writeback kthread stopped, so the chance for a A-A locking on
wq->lockdep_map is disappeared, such A-A deadlock won't happen
any more.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 80265d8dfd77792e133793cef44a21323aac2908 ]
When enable lockdep engine, a lockdep warning can be observed when
reboot or shutdown system,
[ 3142.764557][ T1] bcache: bcache_reboot() Stopping all devices:
[ 3142.776265][ T2649]
[ 3142.777159][ T2649] ======================================================
[ 3142.780039][ T2649] WARNING: possible circular locking dependency detected
[ 3142.782869][ T2649] 5.2.0-rc4-lp151.20-default+ #1 Tainted: G W
[ 3142.785684][ T2649] ------------------------------------------------------
[ 3142.788479][ T2649] kworker/3:67/2649 is trying to acquire lock:
[ 3142.790738][ T2649] 00000000aaf02291 ((wq_completion)bcache_writeback_wq){+.+.}, at: flush_workqueue+0x87/0x4c0
[ 3142.794678][ T2649]
[ 3142.794678][ T2649] but task is already holding lock:
[ 3142.797402][ T2649] 000000004fcf89c5 (&bch_register_lock){+.+.}, at: cached_dev_free+0x17/0x120 [bcache]
[ 3142.801462][ T2649]
[ 3142.801462][ T2649] which lock already depends on the new lock.
[ 3142.801462][ T2649]
[ 3142.805277][ T2649]
[ 3142.805277][ T2649] the existing dependency chain (in reverse order) is:
[ 3142.808902][ T2649]
[ 3142.808902][ T2649] -> #2 (&bch_register_lock){+.+.}:
[ 3142.812396][ T2649] __mutex_lock+0x7a/0x9d0
[ 3142.814184][ T2649] cached_dev_free+0x17/0x120 [bcache]
[ 3142.816415][ T2649] process_one_work+0x2a4/0x640
[ 3142.818413][ T2649] worker_thread+0x39/0x3f0
[ 3142.820276][ T2649] kthread+0x125/0x140
[ 3142.822061][ T2649] ret_from_fork+0x3a/0x50
[ 3142.823965][ T2649]
[ 3142.823965][ T2649] -> #1 ((work_completion)(&cl->work)#2){+.+.}:
[ 3142.827244][ T2649] process_one_work+0x277/0x640
[ 3142.829160][ T2649] worker_thread+0x39/0x3f0
[ 3142.830958][ T2649] kthread+0x125/0x140
[ 3142.832674][ T2649] ret_from_fork+0x3a/0x50
[ 3142.834915][ T2649]
[ 3142.834915][ T2649] -> #0 ((wq_completion)bcache_writeback_wq){+.+.}:
[ 3142.838121][ T2649] lock_acquire+0xb4/0x1c0
[ 3142.840025][ T2649] flush_workqueue+0xae/0x4c0
[ 3142.842035][ T2649] drain_workqueue+0xa9/0x180
[ 3142.844042][ T2649] destroy_workqueue+0x17/0x250
[ 3142.846142][ T2649] cached_dev_free+0x52/0x120 [bcache]
[ 3142.848530][ T2649] process_one_work+0x2a4/0x640
[ 3142.850663][ T2649] worker_thread+0x39/0x3f0
[ 3142.852464][ T2649] kthread+0x125/0x140
[ 3142.854106][ T2649] ret_from_fork+0x3a/0x50
[ 3142.855880][ T2649]
[ 3142.855880][ T2649] other info that might help us debug this:
[ 3142.855880][ T2649]
[ 3142.859663][ T2649] Chain exists of:
[ 3142.859663][ T2649] (wq_completion)bcache_writeback_wq --> (work_completion)(&cl->work)#2 --> &bch_register_lock
[ 3142.859663][ T2649]
[ 3142.865424][ T2649] Possible unsafe locking scenario:
[ 3142.865424][ T2649]
[ 3142.868022][ T2649] CPU0 CPU1
[ 3142.869885][ T2649] ---- ----
[ 3142.871751][ T2649] lock(&bch_register_lock);
[ 3142.873379][ T2649] lock((work_completion)(&cl->work)#2);
[ 3142.876399][ T2649] lock(&bch_register_lock);
[ 3142.879727][ T2649] lock((wq_completion)bcache_writeback_wq);
[ 3142.882064][ T2649]
[ 3142.882064][ T2649] *** DEADLOCK ***
[ 3142.882064][ T2649]
[ 3142.885060][ T2649] 3 locks held by kworker/3:67/2649:
[ 3142.887245][ T2649] #0: 00000000e774cdd0 ((wq_completion)events){+.+.}, at: process_one_work+0x21e/0x640
[ 3142.890815][ T2649] #1: 00000000f7df89da ((work_completion)(&cl->work)#2){+.+.}, at: process_one_work+0x21e/0x640
[ 3142.894884][ T2649] #2: 000000004fcf89c5 (&bch_register_lock){+.+.}, at: cached_dev_free+0x17/0x120 [bcache]
[ 3142.898797][ T2649]
[ 3142.898797][ T2649] stack backtrace:
[ 3142.900961][ T2649] CPU: 3 PID: 2649 Comm: kworker/3:67 Tainted: G W 5.2.0-rc4-lp151.20-default+ #1
[ 3142.904789][ T2649] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/13/2018
[ 3142.909168][ T2649] Workqueue: events cached_dev_free [bcache]
[ 3142.911422][ T2649] Call Trace:
[ 3142.912656][ T2649] dump_stack+0x85/0xcb
[ 3142.914181][ T2649] print_circular_bug+0x19a/0x1f0
[ 3142.916193][ T2649] __lock_acquire+0x16cd/0x1850
[ 3142.917936][ T2649] ? __lock_acquire+0x6a8/0x1850
[ 3142.919704][ T2649] ? lock_acquire+0xb4/0x1c0
[ 3142.921335][ T2649] ? find_held_lock+0x34/0xa0
[ 3142.923052][ T2649] lock_acquire+0xb4/0x1c0
[ 3142.924635][ T2649] ? flush_workqueue+0x87/0x4c0
[ 3142.926375][ T2649] flush_workqueue+0xae/0x4c0
[ 3142.928047][ T2649] ? flush_workqueue+0x87/0x4c0
[ 3142.929824][ T2649] ? drain_workqueue+0xa9/0x180
[ 3142.931686][ T2649] drain_workqueue+0xa9/0x180
[ 3142.933534][ T2649] destroy_workqueue+0x17/0x250
[ 3142.935787][ T2649] cached_dev_free+0x52/0x120 [bcache]
[ 3142.937795][ T2649] process_one_work+0x2a4/0x640
[ 3142.939803][ T2649] worker_thread+0x39/0x3f0
[ 3142.941487][ T2649] ? process_one_work+0x640/0x640
[ 3142.943389][ T2649] kthread+0x125/0x140
[ 3142.944894][ T2649] ? kthread_create_worker_on_cpu+0x70/0x70
[ 3142.947744][ T2649] ret_from_fork+0x3a/0x50
[ 3142.970358][ T2649] bcache: bcache_device_free() bcache0 stopped
Here is how the deadlock happens.
1) bcache_reboot() calls bcache_device_stop(), then inside
bcache_device_stop() BCACHE_DEV_CLOSING bit is set on d->flags.
Then closure_queue(&d->cl) is called to invoke cached_dev_flush().
2) In cached_dev_flush(), cached_dev_free() is called by continu_at().
3) In cached_dev_free(), when stopping the writeback kthread of the
cached device by kthread_stop(), dc->writeback_thread will be waken
up to quite the kthread while-loop, then cached_dev_put() is called
in bch_writeback_thread().
4) Calling cached_dev_put() in writeback kthread may drop dc->count to
0, then dc->detach kworker is scheduled, which is initialized as
cached_dev_detach_finish().
5) Inside cached_dev_detach_finish(), the last line of code is to call
closure_put(&dc->disk.cl), which drops the last reference counter of
closrure dc->disk.cl, then the callback cached_dev_flush() gets
called.
Now cached_dev_flush() is called for second time in the code path, the
first time is in step 2). And again bch_register_lock will be acquired
again, and a A-A lock (lockdep terminology) is happening.
The root cause of the above A-A lock is in cached_dev_free(), mutex
bch_register_lock is held before stopping writeback kthread and other
kworkers. Fortunately now we have variable 'bcache_is_reboot', which may
prevent device registration or unregistration during reboot/shutdown
time, so it is unncessary to hold bch_register_lock such early now.
This is how this patch fixes the reboot/shutdown time A-A lock issue:
After moving mutex_lock(&bch_register_lock) to a later location where
before atomic_read(&dc->running) in cached_dev_free(), such A-A lock
problem can be solved without any reboot time registration race.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 383ff2183ad16a8842d1fbd9dd3e1cbd66813e64 ]
When too many I/O errors happen on cache set and CACHE_SET_IO_DISABLE
bit is set, bch_journal() may continue to work because the journaling
bkey might be still in write set yet. The caller of bch_journal() may
believe the journal still work but the truth is in-memory journal write
set won't be written into cache device any more. This behavior may
introduce potential inconsistent metadata status.
This patch checks CACHE_SET_IO_DISABLE bit at the head of bch_journal(),
if the bit is set, bch_journal() returns NULL immediately to notice
caller to know journal does not work.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e775339e1ae1205b47d94881db124c11385e597c ]
If CACHE_SET_IO_DISABLE of a cache set flag is set by too many I/O
errors, currently allocator routines can still continue allocate
space which may introduce inconsistent metadata state.
This patch checkes CACHE_SET_IO_DISABLE bit in following allocator
routines,
- bch_bucket_alloc()
- __bch_bucket_alloc_set()
Once CACHE_SET_IO_DISABLE is set on cache set, the allocator routines
may reject allocation request earlier to avoid potential inconsistent
metadata.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 1f0ffa67349c56ea54c03ccfd1e073c990e7411e upstream.
When people set a writeback percent via sysfs file,
/sys/block/bcache<N>/bcache/writeback_percent
current code directly sets BCACHE_DEV_WB_RUNNING to dc->disk.flags
and schedules kworker dc->writeback_rate_update.
If there is no cache set attached to, the writeback kernel thread is
not running indeed, running dc->writeback_rate_update does not make
sense and may cause NULL pointer deference when reference cache set
pointer inside update_writeback_rate().
This patch checks whether the cache set point (dc->disk.c) is NULL in
sysfs interface handler, and only set BCACHE_DEV_WB_RUNNING and
schedule dc->writeback_rate_update when dc->disk.c is not NULL (it
means the cache device is attached to a cache set).
This problem might be introduced from initial bcache commit, but
commit 3fd47bfe55b0 ("bcache: stop dc->writeback_rate_update properly")
changes part of the original code piece, so I add 'Fixes: 3fd47bfe55b0'
to indicate from which commit this patch can be applied.
Fixes: 3fd47bfe55b0 ("bcache: stop dc->writeback_rate_update properly")
Reported-by: Bjørn Forsman <bjorn.forsman@gmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Bjørn Forsman <bjorn.forsman@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 31b90956b124240aa8c63250243ae1a53585c5e2 upstream.
Recently people report bcache code compiled with gcc9 is broken, one of
the buggy behavior I observe is that two adjacent 4KB I/Os should merge
into one but they don't. Finally it turns out to be a stack corruption
caused by macro PRECEDING_KEY().
See how PRECEDING_KEY() is defined in bset.h,
437 #define PRECEDING_KEY(_k) \
438 ({ \
439 struct bkey *_ret = NULL; \
440 \
441 if (KEY_INODE(_k) || KEY_OFFSET(_k)) { \
442 _ret = &KEY(KEY_INODE(_k), KEY_OFFSET(_k), 0); \
443 \
444 if (!_ret->low) \
445 _ret->high--; \
446 _ret->low--; \
447 } \
448 \
449 _ret; \
450 })
At line 442, _ret points to address of a on-stack variable combined by
KEY(), the life range of this on-stack variable is in line 442-446,
once _ret is returned to bch_btree_insert_key(), the returned address
points to an invalid stack address and this address is overwritten in
the following called bch_btree_iter_init(). Then argument 'search' of
bch_btree_iter_init() points to some address inside stackframe of
bch_btree_iter_init(), exact address depends on how the compiler
allocates stack space. Now the stack is corrupted.
Fixes: 0eacac22034c ("bcache: PRECEDING_KEY()")
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Rolf Fokkens <rolf@rolffokkens.nl>
Reviewed-by: Pierre JUHEN <pierre.juhen@orange.fr>
Tested-by: Shenghui Wang <shhuiw@foxmail.com>
Tested-by: Pierre JUHEN <pierre.juhen@orange.fr>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Nix <nix@esperi.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 78d4eb8ad9e1d413449d1b7a060f50b6efa81ebd ]
clang has identified a code path in which it thinks a
variable may be unused:
drivers/md/bcache/alloc.c:333:4: error: variable 'bucket' is used uninitialized whenever 'if' condition is false
[-Werror,-Wsometimes-uninitialized]
fifo_pop(&ca->free_inc, bucket);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/md/bcache/util.h:219:27: note: expanded from macro 'fifo_pop'
#define fifo_pop(fifo, i) fifo_pop_front(fifo, (i))
^~~~~~~~~~~~~~~~~~~~~~~~~
drivers/md/bcache/util.h:189:6: note: expanded from macro 'fifo_pop_front'
if (_r) { \
^~
drivers/md/bcache/alloc.c:343:46: note: uninitialized use occurs here
allocator_wait(ca, bch_allocator_push(ca, bucket));
^~~~~~
drivers/md/bcache/alloc.c:287:7: note: expanded from macro 'allocator_wait'
if (cond) \
^~~~
drivers/md/bcache/alloc.c:333:4: note: remove the 'if' if its condition is always true
fifo_pop(&ca->free_inc, bucket);
^
drivers/md/bcache/util.h:219:27: note: expanded from macro 'fifo_pop'
#define fifo_pop(fifo, i) fifo_pop_front(fifo, (i))
^
drivers/md/bcache/util.h:189:2: note: expanded from macro 'fifo_pop_front'
if (_r) { \
^
drivers/md/bcache/alloc.c:331:15: note: initialize the variable 'bucket' to silence this warning
long bucket;
^
This cannot happen in practice because we only enter the loop
if there is at least one element in the list.
Slightly rearranging the code makes this clearer to both the
reader and the compiler, which avoids the warning.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit ce3e4cfb59cb382f8e5ce359238aa580d4ae7778 ]
Currently run_cache_set() has no return value, if there is failure in
bch_journal_replay(), the caller of run_cache_set() has no idea about
such failure and just continue to execute following code after
run_cache_set(). The internal failure is triggered inside
bch_journal_replay() and being handled in async way. This behavior is
inefficient, while failure handling inside bch_journal_replay(), cache
register code is still running to start the cache set. Registering and
unregistering code running as same time may introduce some rare race
condition, and make the code to be more hard to be understood.
This patch adds return value to run_cache_set(), and returns -EIO if
bch_journal_rreplay() fails. Then caller of run_cache_set() may detect
such failure and stop registering code flow immedidately inside
register_cache_set().
If journal replay fails, run_cache_set() can report error immediately
to register_cache_set(). This patch makes the failure handling for
bch_journal_replay() be in synchronized way, easier to understand and
debug, and avoid poetential race condition for register-and-unregister
in same time.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 631207314d88e9091be02fbdd1fdadb1ae2ed79a ]
journal replay failed with messages:
Sep 10 19:10:43 ceph kernel: bcache: error on
bb379a64-e44e-4812-b91d-a5599871a3b1: bcache: journal entries
2057493-2057567 missing! (replaying 2057493-2076601), disabling
caching
The reason is in journal_reclaim(), when discard is enabled, we send
discard command and reclaim those journal buckets whose seq is old
than the last_seq_now, but before we write a journal with last_seq_now,
the machine is restarted, so the journal with the last_seq_now is not
written to the journal bucket, and the last_seq_wrote in the newest
journal is old than last_seq_now which we expect to be, so when we doing
replay, journals from last_seq_wrote to last_seq_now are missing.
It's hard to write a journal immediately after journal_reclaim(),
and it harmless if those missed journal are caused by discarding
since those journals are already wrote to btree node. So, if miss
seqs are started from the beginning journal, we treat it as normal,
and only print a message to show the miss journal, and point out
it maybe caused by discarding.
Patch v2 add a judgement condition to ignore the missed journal
only when discard enabled as Coly suggested.
(Coly Li: rebase the patch with other changes in bch_journal_replay())
Signed-off-by: Tang Junhui <tang.junhui.linux@gmail.com>
Tested-by: Dennis Schridde <devurandom@gmx.net>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 68d10e6979a3b59e3cd2e90bfcafed79c4cf180a ]
When failure happens inside bch_journal_replay(), calling
cache_set_err_on() and handling the failure in async way is not a good
idea. Because after bch_journal_replay() returns, registering code will
continue to execute following steps, and unregistering code triggered
by cache_set_err_on() is running in same time. First it is unnecessary
to handle failure and unregister cache set in an async way, second there
might be potential race condition to run register and unregister code
for same cache set.
So in this patch, if failure happens in bch_journal_replay(), we don't
call cache_set_err_on(), and just print out the same error message to
kernel message buffer, then return -EIO immediately caller. Then caller
can detect such failure and handle it in synchrnozied way.
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 95f18c9d1310730d075499a75aaf13bcd60405a7 ]
In the CACHE_SYNC branch of run_cache_set(), LIST_HEAD(journal) is used
to collect journal_replay(s) and filled by bch_journal_read().
If all goes well, bch_journal_replay() will release the list of
jounal_replay(s) at the end of the branch.
If something goes wrong, code flow will jump to the label "err:" and leave
the list unreleased.
This patch will release the list of journal_replay(s) in the case of
error detected.
v1 -> v2:
* Move the release code to the location after label 'err:' to
simply the change.
Signed-off-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 1bee2addc0c8470c8aaa65ef0599eeae96dd88bc upstream.
In journal_reclaim() ja->cur_idx of each cache will be update to
reclaim available journal buckets. Variable 'int n' is used to count how
many cache is successfully reclaimed, then n is set to c->journal.key
by SET_KEY_PTRS(). Later in journal_write_unlocked(), a for_each_cache()
loop will write the jset data onto each cache.
The problem is, if all jouranl buckets on each cache is full, the
following code in journal_reclaim(),
529 for_each_cache(ca, c, iter) {
530 struct journal_device *ja = &ca->journal;
531 unsigned int next = (ja->cur_idx + 1) % ca->sb.njournal_buckets;
532
533 /* No space available on this device */
534 if (next == ja->discard_idx)
535 continue;
536
537 ja->cur_idx = next;
538 k->ptr[n++] = MAKE_PTR(0,
539 bucket_to_sector(c, ca->sb.d[ja->cur_idx]),
540 ca->sb.nr_this_dev);
541 }
542
543 bkey_init(k);
544 SET_KEY_PTRS(k, n);
If there is no available bucket to reclaim, the if() condition at line
534 will always true, and n remains 0. Then at line 544, SET_KEY_PTRS()
will set KEY_PTRS field of c->journal.key to 0.
Setting KEY_PTRS field of c->journal.key to 0 is wrong. Because in
journal_write_unlocked() the journal data is written in following loop,
649 for (i = 0; i < KEY_PTRS(k); i++) {
650-671 submit journal data to cache device
672 }
If KEY_PTRS field is set to 0 in jouranl_reclaim(), the journal data
won't be written to cache device here. If system crahed or rebooted
before bkeys of the lost journal entries written into btree nodes, data
corruption will be reported during bcache reload after rebooting the
system.
Indeed there is only one cache in a cache set, there is no need to set
KEY_PTRS field in journal_reclaim() at all. But in order to keep the
for_each_cache() logic consistent for now, this patch fixes the above
problem by not setting 0 KEY_PTRS of journal key, if there is no bucket
available to reclaim.
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 5b5fd3c94eef69dcfaa8648198e54c92e5687d6d ]
Current code already uses d_strtoul_nonzero() to convert input string
to an unsigned integer, to make sure writeback_rate_p_term_inverse
won't be zero value. But overflow may happen when converting input
string to an unsigned integer value by d_strtoul_nonzero(), then
dc->writeback_rate_p_term_inverse can still be set to 0 even if the
sysfs file input value is not zero, e.g. 4294967296 (a.k.a UINT_MAX+1).
If dc->writeback_rate_p_term_inverse is set to 0, it might cause a
dev-zero error in following code from __update_writeback_rate(),
int64_t proportional_scaled =
div_s64(error, dc->writeback_rate_p_term_inverse);
This patch replaces d_strtoul_nonzero() by sysfs_strtoul_clamp() and
limit the value range in [1, UINT_MAX]. Then the unsigned integer
overflow and dev-zero error can be avoided.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 596b5a5dd1bc2fa019fdaaae522ef331deef927f ]
Currently sysfs_strtoul_clamp() is defined as,
82 #define sysfs_strtoul_clamp(file, var, min, max) \
83 do { \
84 if (attr == &sysfs_ ## file) \
85 return strtoul_safe_clamp(buf, var, min, max) \
86 ?: (ssize_t) size; \
87 } while (0)
The problem is, if bit width of var is less then unsigned long, min and
max may not protect var from integer overflow, because overflow happens
in strtoul_safe_clamp() before checking min and max.
To fix such overflow in sysfs_strtoul_clamp(), to make min and max take
effect, this patch adds an unsigned long variable, and uses it to macro
strtoul_safe_clamp() to convert an unsigned long value in range defined
by [min, max]. Then assign this value to var. By this method, if bit
width of var is less than unsigned long, integer overflow won't happen
before min and max are checking.
Now sysfs_strtoul_clamp() can properly handle smaller data type like
unsigned int, of cause min and max should be defined in range of
unsigned int too.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit c3b75a2199cdbfc1c335155fe143d842604b1baa ]
dc->writeback_rate_i_term_inverse can be set via sysfs interface. It is
in type unsigned int, and convert from input string by d_strtoul(). The
problem is d_strtoul() does not check valid range of the input, if
4294967296 is written into sysfs file writeback_rate_i_term_inverse,
an overflow of unsigned integer will happen and value 0 is set to
dc->writeback_rate_i_term_inverse.
In writeback.c:__update_writeback_rate(), there are following lines of
code,
integral_scaled = div_s64(dc->writeback_rate_integral,
dc->writeback_rate_i_term_inverse);
If dc->writeback_rate_i_term_inverse is set to 0 via sysfs interface,
a div-zero error might be triggered in the above code.
Therefore we need to add a range limitation in the sysfs interface,
this is what this patch does, use sysfs_stroul_clamp() to replace
d_strtoul() and restrict the input range in [1, UINT_MAX].
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
